Just as the title says. I loved Tyranny. It really made me feel like I was "evil", not just some jerkoff that demands money from good deeds while kicking puppies.

If I go into this wanting to be an evil character, will I be disappointed? I know this is BioWare, so I'm kinda iffy.

Side note: how's the romance?

You can be evil "on paper" but there aren't many instances that lets you - apart from just killing innocent people.
At the very end of the whole saga you can do something rather evil, but all in all...No. BG does not do Evil well.

As for the romances. They are pretty ok. They only pop up in BG2, and they are rather straightforward. I think BG2 was one of the first games that had romances, so it is early days when it comes to that.

Yeah, in the dialog you're typically only given the option to be a mean, selfish jerk rather than being truly evil. There are a few quests that do allow an evil resolution or that are just flat-out evil quests from the get-go (being hired for murder or burglary, etc.) But those are more the exception than the rule.

You can certainly have evil motivations for what you're doing, and the story works fine with that. And you have the freedom to commit evil deeds like randomly pick pocketing someone, robbing a home or even murdering some random NPC. Of course, if you make that a recurring habit then all the town guards are going to attack you on sight, and at extreme levels you'll even have parties of bounty hunters pursuing you.

But the main narrative isn't really designed around progressively building yourself up as a villain, other than being able to pop some evil responses at a few key plot points. Trying to be evil doesn't fundamentally alter the overall course of events in the story, other than -- as Stig mentioned -- at the very end.

Evil characters do have disadvantages, like raised store prices. But they do get a bunch of bonuses as well. When your reputation gets low enough, the Flaming Fist will conduct a manhunt for you. This guarantees a steady flow of XP and cash.

Evil characters are also stronger. Eldoth's poison arrow and initial spell loadout (larloch's minor drain, magic missile, and horror) makes him superior to his chaotic neutral counterpart, Garrick. Edwin gets gamebreaking gear, making him the best spellcaster in both games. Give Viconia aishadeena, gauntlets of ogre strength, plate mail and a tower shield, and she becomes a juggernaut.

There's also the equipment. Neb's nasty cutter is a good dagger that can hit anything (with the exception of a few creatures who need a +3 weapon), human flesh is the pretty much the strongest armour in the game (after upgrading it to +5), and you can also get Blackrazor.

One of the "conservative" rule modifications (see the sticky) is to give discounts if you have a very high or a very low reputation. To me that makes a lot of thematic sense, so I installed it even though I'm playing a Paladin LOL.

Does that get better in game? Because I tried that and they only give 35xp each and only drop plate mail. Not really a flow of XP and cash but definitely annoying.

They don't have that much in a single encounter, but it stacks up over time.

The XP from Flaming Fist mercs isn't much, but good and neutral characters get zero, since they aren't hunted by the Flaming Fist.

You don't need to be evil to recruit the evil characters, but you do need to be evil to keep them.

The tick from Eldoth's poison arrow can shut down casters. The same goes for Neb's nasty cutter. If you back stab a mage with Neb's dagger and the mage survives the attack, the DoT will chew away at the few hit points he has left. The adventurer's mart doesn't sell a back stab weapon with a similar effect. Remember to give your thief non-detection; NPCs in the game will cast true sight when your cloaked thief is creeping around.

Human flesh (+5) gives an AC bonus of 3 (5 vs piercing and missiles), +4 to saving throws, +20% to move silently, and 20% magic resistance. Blackrazor is a +3 longsword. Each hit has a 15% chance of draining 4 levels, healing you by 20 HP, giving you haste, and increasing your strength by 3 points for 20 seconds. On top of that you get regeneration of 1 hp every 5 seconds, and you get immunity to charm and fear. The regeneration and immunity to fear/charm is a passive effect.

No, you just need to not be a mighty force for good. Which means keeping your rep below 19. Or using a mod that deals with the rep based leave trigger.

Blackrazor is admittedly a very nice weapon, but overall I think the game is quite heavily biased towards "good" parties. Store prices is one example, but if you also are "evil" (rude) in conversations, you'll miss out on many quests.

I think some of the best characters are towards the evil bend though, like Edwin. Then you have Viconia and Korgan, both excellent, and fun and interesting too.

understand that there is a big difference between EVIL and "low rep"
Yes you can be evil and its very rewarding play style... what you can't get away with (for very long) is low rep.

Nope, if you are playing normally and doing the optional dungeons as well, you are going to hit the level cap by the time you hit the final chapter. Long term, there is nothing to be gained from having the FF chasing your arse around the Sword Coast. Nope, you just need to do something stupid (ie, kill a random commoner for no reason) once your rep gets too high or turn into the slayer. The problem here is rep (which is too easy to raise by playing the game normally) and only easy to lose when you're playing stupidly (ie. random killing). You don't need to be evil to recruit Eldoth and anyone who can use a bow can use arrows of biting. You want to know a smarter way to bring down casters? Bringing your entire party to focus fire on them. Once again, there's no advantage of being "evil" here Unless you are playing a solo character, there is absolutely no reason to back stab. If you are tackling a mage (or anyone) who is accompanied by a mob, guess who they are going to target after the thief becomes visible? If the mage is alone, why bother backstabbing in the first place? Overwhelming the caster by bringing your entire party down on them is much more efficient. In BG2, I can't recall a single mage who was a problem to deal with, even Irenicus is a push over. As long as you have a way to bring down their spell protections, most times, they will be dead before the round is over. Once again, no benefits for being "evil" here.

Oh, and if you are dead set on using Neb's Cutter, you don't need to RP evil to get it either.

None of these are advantages when you consider being an asshole in dialog can cut you off from XP and loot. In fact most of the "advantages" you mentioned are still open for "good" parties as long as your rep isn't too high. But it's fine, I already mentioned in order to find advantages for being "evil" in BG, we would have to scrape the bottom of the barrel and that's exactly what we're doing.

Once you get far enough in Baldur's Gate 2 (and assuming you don't use a glitch to skip Spellhold), you will get an ability that, when used, has the drawback of lowering your rep.

There's also one character who lowers your rep when she joins, so if you dismiss and re-recruit her, your rep will be low enough to not have evil characters leave. Unfortunately, this also breaks any romance you might have started with her (if that's your thing).

Or if you're speedrunning. Having Yoshimo transform into an Iron Golem, go behind Irenicus before he spawns, and then have him backstab can kill Irenicus before the battle really has a chance to start.

If you don't have a Yoshimo who can transform (that is, if you didn't trick the game into letting you do this), this can be done glitchless with any thief/mage except possibly the main character.

The Irenicus fight is somewhat of a special case because he spawns as an event instead of being present on the map from the start; similar tricks could work in other similar fights. Traps (including spells like Skull Trap) can be used in a similar manner. There's also the fact that the Irenicus fight ends as soon as you kill him, so even though he is accompanied by other enemies, once he's dead, you don't have to worry about those other enemies.

Yup, the Slayer ability, covered that already

With that character though, you only lose the rep once you accept her into the party. You gain the rep back once you kick her out.

Fair enough, I never considered back stabbing for speed running or glitches (neither are really my thing). The OP was asking about the viability of RPing an evil character in BG so its unlikely they would be considering speed running or glitches.